<!DOCTYPE html>
<html>
<head>
  <style>

  table {
    background:#eeeeee;
  }
  </style>
  <script src="http://code.jquery.com/jquery-latest.js"></script>
</head>
<body>
  <table border="1">
    <tr style="background-color:#bbbbff;"><td>Row with Index #0</td></tr>
    <tr><td>Row with Index #1</td></tr>

    <tr style="background-color:#bbbbff;"><td>Row with Index #2</td></tr>
    <tr><td>Row with Index #3</td></tr>
  </table>
<script>$("tr:even").css("background-color", "#bbbbff");</script>

</body>
</html>